Circuit and method for rake training during acquisition

ABSTRACT

A method is provided for training a rake finger ( 200 ). In this method the rake finger receives a data signal including a plurality of signal components having a plurality of signal phase values, respectively. ( 620 ). The rake finger then sets a current acquisition phase for a locally-generated signal ( 620 ) and then calculates a value of an autocorrelation function for the received data signal with the locally-generated signal at the current acquisition phase. ( 630 ). The rake finger determines when the autocorrelation function is at a peak value ( 640 ), saving the peak value in a storage device ( 290 ) when the autocorrelation function is at the peak value ( 650 ). The rake finger can then set a finger weight (W) for the rake finger based on the peak value stored in the storage device. This method can be performed at least in part during an acquisition process for the rake finger.

CROSS-REFERENCE TO RELATED PATENT DOCUMENTS

This application is related to U.S. application Ser. No. 10/214,183,filed Oct. 10, 2000, entitled “Mode Controller For Signal AcquisitionAnd Tracking In An Ultra Wideband Communication System,” published onApr. 4, 2003, as U.S. Patent Application Publication No. US 2003-0067963A1, and issued on Sep. 19, 2006, as U.S. Pat. No. 7,110,473.

FIELD OF THE INVENTION

The present invention relates in general to communication systems, suchas ultra wideband (UWB) systems, including wireless mobile transceivers,centralized transceivers, related equipment, and corresponding methods.In particular, the present invention relates to a wireless receiver thatuses multiple receiver circuits to perform a raking operation onincoming multipath signal copies to increase the accuracy of signalprocessing. Another aspect of the present invention relates to a methodand circuit by which the weights of individual rake fingers are trainedduring an acquisition process to reduce or eliminate a training periodperformed during a data processing period.

BACKGROUND OF THE INVENTION

In receiver architectures in which a transmitted signal can takemultiple paths to arrive at the receiver, such as in a wirelessenvironment, a process known as raking can be used to maximize theaccuracy of processing of an incoming signal. In a raking process,multiple raking fingers within a single receiver process differentincoming multipath signal copies. Each raking finger produces a signalestimate, which is then weighted according to its predicted accuracy.The weighted estimates from each of the raking fingers are then summedto generate a predicted value for the incoming signal.

When performing a raking process, it is necessary to determine theweights that should be used for the various raking fingers. In order togenerate weighting values that accurately reflect the predicted accuracyof each raking finger, it is generally necessary to perform a trainingprocess during which a known signal pattern is transmitted. During thistraining process, the accuracy of each raking finger in detecting theknown pattern can be evaluated, and so the weights of each finger can beproperly assigned.

In one rake training method, each raking finger includes a codeprocessor that provides an estimated value for the multipath signalincoming to that finger. The code processor does this by comparingwavelets in an incoming signal to locally-generated wavelets. However,in order for such a code processor to produce valid signal estimates, itis necessary for a local clock that generates the local wavelets to beproperly synchronized in phase with the clock for the incoming multipathsignal. As a result, it is necessary to wait until an acquisitionprocess has been completed before rake training can be performed.

Prior to the completion of the acquisition process, the phase of thelocal clock is not properly matched to the transmitter clock thatcreated the incoming signal, and may even be constantly altered to allowthe acquisition process to identify the phase of the transmitter clock.

It would therefore be desirable to allow for a rake training method thatcould be performed during an acquisition process. In this way, theweights of the raking fingers could be determined during acquisition, atime period where no data processing could be done regardless. Thus, notime after acquisition would be required for rake training, and theentire data receiving process could be performed more quickly.

BRIEF DESCRIPTION OF THE DRAWINGS

The accompanying figures, where like reference numerals refer toidentical or functionally similar elements throughout the separate viewsand which together with the detailed description below are incorporatedin and form part of the specification, serve to further illustratevarious embodiments and to explain various principles and advantages inaccordance with the present invention.

FIG. 1 is a block diagram of a wireless system using a three-channelraking receiver, according to a disclosed embodiment of the presentinvention;

FIG. 2 is a block diagram of a raking finger according to one disclosedembodiment of the present invention;

FIG. 3 is a block diagram of an exemplary analog receiver according to adisclosed embodiment;

FIG. 4 is a block diagram of an exemplary analog receiver according to adisclosed embodiment;

FIG. 5 is a block diagram of a receiver including N raking fingersaccording to a disclosed embodiment of the present invention; and

FIG. 6 is a flow chart of a rake training process for one raking fingeraccording to a disclosed embodiment of the present invention.

DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS

Rake Receiver

FIG. 1 is a block diagram of a wireless system using a three-channelraking receiver, according to a disclosed embodiment of the presentinvention. As shown in FIG. 1, the system 100 includes a transmittingdevice 105 having a first antenna 115 and a receiving device 110 havinga receiving antenna 120. The receiving device 110 includes first,second, and third raking fingers 145A, 145B, and 145C, an alignmentcircuit 170, and a summer 180. The first, second, and third rakingfingers 145A, 145B, and 145C, each respectively include first, second,and third raking receivers 150A, 150B, and 150C, and first, second, andthird weighting mixers 160A, 160B, and 160C. Each of the raking fingers145A-145C can also be referred to as raking channels, raking arms, orany other term used to designate separate rake elements.

The receiving device 105 receives a signal sent from the transmittingdevice 110 along multiple signal paths 132, 134, 136, 140, and uses athree channel rake process for processing the signal transmitted fromthe transmitting device 105. As shown in FIG. 1, the signal paths can bea direct path 140 or reflected paths 132, 134, 136 that bounce off ofone or more nearby objects 122, 124, 126. Although only three reflectedsignal paths 132, 134, and 136 are shown, many more paths will generallyexist. Only three reflected signal paths 132, 134, and 136 are shown forsimplicity of disclosure.

The first through third channel receivers 150A-150C in the first throughthird raking fingers 145A-145C, each receive respective signals from thereceiving antennae 120, but process the received signals differently.

In the embodiment disclosed in FIG. 1, the receiving antennae 120 isattached to the first, second, and third channel receivers 150A-150C inthe receiving device 110, each of which channel receiver 150A-150C tunesinto a particular multipath signal.

The first, second and third channel receivers 150A-150C respectivelyoutput first, second, and third data signals D₁, D₂, and D₃, which arethen respectively weighted by first, second, and third weight values W₁,W₂, and W₃ to form first, second, and third weighted data signals WD₁,WD₂, and WD₃, through the first through third weighting mixers160A-160C.

The first through third weighted data signals WD₁-WD₃ are then alignedin phase using an alignment circuit 170. This alignment is necessary tomake certain that the multipath signals being processed by each finger150A-150C are aligned to the same position within the data stream withrespect to each other. Because the various possible signal paths 132,134, 136, 140 may have different lengths, multipath signals may arriveat the receiving antenna 120 at different phases with respect to eachother. The alignment circuit delays the signals to match the slowestmultipath component so that they are all processed at the same phase.

Although disclosed in FIG. 1 as being after the first through thirdweighting mixers 160A-160C, in alternate embodiments the alignmentcircuit 170 could be formed prior to the first through third weightingmixers 160A-160C.

The aligned and weighted multipath components are then added together ina summer 180, which outputs a final estimate for the data values fromthe incoming signal.

The first through third weights W₁-W₃ used in the receiving device 110of FIG. 1 are used to account for the variance of the received wavelets.If a large wavelet is correlated at one raking finger, that large signalwill receive a greater weight than a smaller wavelet received at anotherraking finger. This higher weight indicates that the signal received atthat particular finger is more likely to be the correct signal.

The raking finger with the highest weight will be identified as having areceived wavelet that produces a bit estimate with a low probability oferror. The other raking fingers are identified as receiving waveletsthat provide bit values with correspondingly greater errors, and so theyhave smaller weights. However, if the raking fingers have been trainedproperly, when the system combines the three weighted signals thecombined result will have a lower probability of error than the outputof any one of the raking fingers by itself (even the raking finger withthe lowest error).

Because the summer 180 adds values output from the first through thirdweighting mixers 160A-160C, the final result has information from allthree raking channels. And because each of the first through third datasignals D₁-D₃ are weighted by the first through third weighting signalsW₁-W₃, respectively, the more accurate arms contribute more to theresulting bit value output from the summer 180. In the case where allthee signal paths have equal weights, the RAKE can provide 10*log₁₀ (3)dB gain, which is significant.

In some embodiments the first through third weighting signals W₁-W₃ willbe normalized to some value, e.g., such that they sum to one. However,what is of primary importance is the ratio between the first throughthird weighting signals W₁-W₃, which indicates their relative weightswith respect to each other.

Consider the following example in which the receiving device 110 of FIG.1 receives delayed wavelets traveling along signal paths 132, 134, 136,and 140. In this example, the first channel receiver 150A locks onto thesecond strongest wavelet, the second channel receiver 150B locks ontothe strongest wavelet, and the third channel receiver 150C locks ontothe third strongest wavelet. The fourth strongest wavelet is not lockedonto because it is the smallest of all four of the multipath wavelets,and the receiving device 110 only has three raking channels.

The first channel receiver 150A produces a first data value D₁, thesecond channel receiver 150B produces a second data value D₂, and thethird channel receiver 150C produces a third data value D₃.

Because the second channel receiver 150B processes the strongestwavelet, the second data value D₂ will be weighted the highest.Similarly, because the first channel receiver 150A processes the secondstrongest wavelet, the first data value D₁ will be weighted the secondhighest. Finally, because the third channel receiver 150C processes thethird strongest of the processed wavelets, the third data value D₃ willbe weighted the lowest. Thus, W₂>W₁>W₃.

Alternate embodiments could vary which receiver 150A-150C receives thestrongest, second strongest, and third strongest multipath wavelets. Andin some cases multipath wavelets could be coincident with each other,reducing the number of available multipath wavelets.

Although the preferred embodiment of FIG. 1 discloses three rakingreceivers 150A-150C, alternate embodiments could expand this to N rakingreceivers, where N is an integer greater than one. In this case each ofthe N receiver outputs will be weighted by a respective first throughN^(th) weight value W₁-W_(N).

In addition, although FIG. 1 discloses a transmitting device 110 and areceiving device 120, either or both of these devices can betransceivers.

Raking Finger

FIG. 2 is a block diagram of a raking finger according to one disclosedembodiment of the present invention. As shown in FIG. 2, the rakingfinger 200 includes a channel receiver 210, a mixer 260, a matchedfilter circuit 270, a peak detector 280, and a storage element 290. Thechannel receiver 210 further includes an analog receiver 220, ananalog-to-digital converter 230, a code processor 240, and an alignmentcircuit 250.

The analog receiver 220 receives an incoming multipath signal from anantenna and performs all necessary analog processing. This can includefiltering, gain control, and other front end processing.

FIG. 3 is a block diagram of an exemplary analog receiver 220 accordingto a disclosed embodiment. As shown in FIG. 3, the analog receiver 220includes front end circuitry 310, a local oscillator (LO) mixer 320, anda sample-hold-dump (SHD) integrator 330. Alternate embodiments caninclude a filter after the SHD integrator 330.

The front end circuitry 310 performs all necessary front end processingon the incoming multipath signal. This can include filtering, gaincontrol, and the like.

The LO mixer 320 mixes the incoming signal with a locally generatedsignal. During an alignment process the locally-generated signal isaligned in phase and frequency with the incoming signal. Once properlyaligned, the output of the LO mixer 320 can be used by the codeprocessor 240 to create a maximum correlation value between the incomingsignal and the locally-generated signal.

The SHD integrator 330 integrates the mixed signal output from the LOmixer 320 to provide integrated signal values at a set sample rate.These integrated signal values result in solid digital values in laterprocessing. In some embodiments, the sample rate for the LO mixer 320will be set at the wavelet duration for the incoming multipath signal.In this way, once properly aligned, each value output from the SHDintegrator 330 will correspond to one wavelet.

The analog signal output from the analog receiver is converted to adigital signal by the analog-to-digital converter (ADC) 230 for furtherprocessing. The digital output from the ADC 230 includes signalcomponents and a noise component.

The code processor 240 in the raking finger 200 receives the digitalsignal output from the ADC 230 (which corresponds to an integrated anddigitized version of the output of the LO mixer 320) and uses thissignal to generate an estimated data signal D once an acquisitionprocess is completed. In operation, the code processor 240 multipliesthe digital signal output from the ADC 230 with a known chip sequencethat corresponds to one data bit and sums the result over one bitperiod. Each sample output by the code processor is also made up of asignal portion and a noise portion.

The alignment circuit 250 works in conjunction with alignment circuitsin other raking fingers to align the estimate of the multipath signalbeing processed by the current raking finger 200 with multipath signalsbeing processed by the other raking fingers, to create an aligned dataestimate D.

Although the alignment circuit 250 in this embodiment is disclosed asbeing within the channel receiver 210, in alternate embodiments it couldbe provided outside of the channel receiver 210, either before or afterthe mixer 260.

The mixer 260 receives the aligned data estimate D and mixes it with theweight W associated with the current raking finger 200 to produce aweighted data estimate WD. This weighted data estimate WD is thenprovided to a rake processor for summing with other weighted dataestimates from other raking fingers.

The matched filter circuit 270 is designed to have an impulse responsethat fully matches or closely matches the autocorrelation function of anincoming wavelet or code word and a locally-generated wavelet or codeword. This autocorrelation function has a maximum value when theincoming signal and the locally-generated signal are matched in phasewith each other (i.e., when the phase offset between them is zero).

Thus, the matched filter circuit 270 convolves the output of the codeprocessor 240 with the known autocorrelation function (or anapproximation of the autocorrelation function) to produce a detectionvalue that is used for acquisition.

The output of the matched filter 270 is monitored to determine thelocation of the peaks in the filtered autocorrelation value. The maximumof the peaks is compared to a threshold value to determine whether anadequate signal is present for reception. This threshold value may be afixed value or a variable threshold that adapts to background noise.

In one embodiment the matched filter 270 is an infinite impulse response(IIR) filter, though in alternate embodiments other sorts of filters canbe used (e.g., a finite impulse response (FIR) filter).

Because the matched filter 270 is matched to the autocorrelationfunction, its output provides a good estimate of the amplitude of theincoming signal when its output is at a peak. And since the relativestrength (i.e., amplitude) of the incoming multipath signal compared toother incoming multipath signals is what determines the weighting valueW, the peak output of the matched filter 270 can be used to set theweighting value W.

The peak detector 280 operates to detect local peaks in the output ofthe matched filter 270. And when it finds a peak, the peak detector 280instructs the storage element 290 to store both the peak value and thecurrent phase of the peak. One way to accomplish this is by having thepeak detector 280 detect when the slope of the output of the matchedfilter 270 changes sign. Another way is to divide the output of thematched filter into sectors and find the maximum values in each sector.Other ways of peak detection (sometimes called “bump hunting”) would beknown to one skilled in the art, and may be used to implement the peakdetector 280.

The storage element 290 stores one or more peak value and phase locationpairs corresponding to peak values output from the matched filter, asinstructed by the peak detector 280. When the raking finger 210determines what multipath signal it will process, that multipath signalwill have an associated phase. In order to determine the weighting valueW that should be used with the selected multipath signal, the rakingfinger 210 need only look in the storage element 290 to see what matchedfilter peak value is associated with the phase value corresponding tothe selected multipath signal and use that peak value as the weightingvalue W.

Acquisition Process

As noted above, during an acquisition process an incoming signal ismixed with a locally-generated signal (which is a copy of the incomingsignal) as the locally-generated signal is shifted in phase throughout aset phase range (e.g., 2π radians of phase). The resultingautocorrelation signal is monitored to determine where a maximum pointof the autocorrelation signal appears. The phase at which this maximumpoint occurs in the autocorrelation signal corresponds to a desiredacquisition phase.

One advantageous way to detect peaks in the autocorrelation signal is topass the autocorrelation signal through a matched filter that is matchedto the shape of the autocorrelation function. As noted with respect tothe description of the matched filter circuit 270, this matched filtercan be an FIR filter or an IIR filter. An FIR filter can be set toexactly match the autocorrelation function, but will generally be morecomplicated than an IIR filter. In contrast, an IIR filter will be lesscomplex than an FIR filter, but will only provide an approximation ofthe autocorrelation function. In practice, either implementation canwork, depending upon system requirements. The filter has the effect ofreducing the noise, allowing the true maximum to be found and also abetter estimate of the maximum value.

Since the output of the matched filter 270 has reduced noise andprovides a better estimate of the peak input value, the output of thematched filter 270 can be used for rake training during the acquisitionprocess. There is no need to wait until acquisition is completed beforerake training can begin. As a result, rake training can be started, andmay even be completed during the acquisition process.

Scaling of Weighting Values

As noted above, the weighting values provided to the mixer 260 in FIG. 2can be scaled. FIG. 4 is a block diagram of a raking finger using ascaled weighting value according to one disclosed embodiment of thepresent invention. As shown in FIG. 4, the raking finger 400 includes achannel receiver 210, a mixer 260, a matched filter circuit 270, a peakdetector 280, and a storage element 290, and a scaling circuit 410. Thechannel receiver further includes an analog receiver 220, ananalog-to-digital converter 230, a code processor 240, and an alignmentcircuit 250.

The elements in FIG. 4 that are common to FIG. 2 operate as describedabove with respect to FIG. 2. In addition, the scaling circuit 410 isprovided between the storage element 290 and the mixer 260.

The scaling circuit 410 multiplies the output of the storage element 290by a scaling factor N, to provide a scaled weighting factor W. Thescaling factor can be any value desired. In one embodiment the scalingfactor is one divided by the sum of all of the unscaled weightingfactors. In this way the weights are scaled such that they sum to one.In other embodiments the scaling factor can be any number, includingfractions.

Receiver Circuit

FIG. 5 is a block diagram of a receiver including K raking fingersaccording to a disclosed embodiment of the present invention. As shownin FIG. 5, the receiver 500 includes an antenna 205, first throughK^(th) raking fingers 200A-200C, and an acquisition and rake processor510.

The antenna receives a plurality of multipath signals and provides themto each of the first through K^(th) raking fingers 200A-200C.

The first through K^(th) raking fingers 200A-200C each operate asdescribed above with respect to FIG. 2. Each receives the plurality ofmultipath signals and provides a weighted data value WD₁-WD_(K), and amatched filter output C₁(n)-C_(K)(n) to the acquisition and rakeprocessor 510.

During an acquisition mode, the rake processor 510 monitors the firstthrough K^(th) matched filter outputs to determine the phases associatedwith the K largest incoming multipath signals. The acquisition and rakeprocessor 510 can then use this information to instruct the firstthrough K^(th) raking fingers 200A-200C which multipath signals theyshould process.

During a data processing mode, the acquisition and rake processor 510sums the first through K^(th) weighted data estimates to provide a finaldata estimate.

Raking Process

FIG. 6 is a flow chart of a rake training process for one raking fingeraccording to a disclosed embodiment of the present invention. As shownin FIG. 6, the rake training process is performed during an acquisitionprocess, which eliminates the need to lose time after acquisition forrake training.

The rake training process begins when the raking finger receives anincoming signal. (610) This signal will contain a plurality of multipathcomponents.

The raking finger then sets the current acquisition phase (620) andprocesses the received signal through the circuitry in the raking finger(e.g., as shown above in FIG. 2), to ultimately provide anautocorrelation response at the matched filter. (630)

The raking finger will then determine whether the autocorrelationresponse output from the matched filter is a peak value. (640) Asdisclosed above, this can be performed by recording the maximum outputvalue over each section of the set of possible code phases, or bydetecting when the phase of the derivative of the matched filter changesfrom positive to negative.

If the output of the matched filter is a peak value, the raking fingerwill store the peak output value and the current phase location of thematched filter (650) and then proceed to determine whether the signalhas been acquired (660) (i.e., whether the acquisition process iscompleted).

If the output of the matched filter is not a peak value, the rakingfinger will simply determine whether the acquisition process has beencompleted (660).

If the acquisition process has not been completed, the raking fingerwill adjust the current acquisition phase to a new acquisition phase(670) and process the received signal at the new acquisition phase(630).

If, however, the signal has been acquired (i.e., the acquisition processis completed), the raking finger will select the phase of the multipathsignal it should process (680) (i.e., the phase of the matched filterpeak associated with that multipath signal). The raking finger will thenproceed to process the incoming signal using the stored finger weightassociated with the phase of the selected multipath signal. (690)

Each of the raking fingers can simultaneously perform the same processover non-overlapping code phases. Thus, the entire codewheel is rapidlyspanned, acquisition is performed, and all rake fingers are trained atthe same time.

CONCLUSION

This disclosure is intended to explain how to fashion and use variousembodiments in accordance with the invention rather than to limit thetrue, intended, and fair scope and spirit thereof. The foregoingdescription is not intended to be exhaustive or to limit the inventionto the precise form disclosed. Modifications or variations are possiblein light of the above teachings. The embodiment(s) was chosen anddescribed to provide the best illustration of the principles of theinvention and its practical application, and to enable one of ordinaryskill in the art to utilize the invention in various embodiments andwith various modifications as are suited to the particular usecontemplated. All such modifications and variations are within the scopeof the invention as determined by the appended claims, as may be amendedduring the pendency of this application for patent, and all equivalentsthereof, when interpreted in accordance with the breadth to which theyare fairly, legally, and equitably entitled. The various circuitsdescribed above can be implemented in discrete circuits or integratedcircuits, as desired by implementation.

1. A method of training a rake finger, at least in part during an acquisition process for the rake finger, comprising: receiving a data signal including a plurality of signal components having a plurality of signal phase values, respectively; setting a current acquisition phase for a locally-generated signal; calculating a value of an autocorrelation function for the received data signal with the locally-generated signal at the current acquisition phase; determining when the autocorrelation function is at a peak value; saving the peak value in a storage device when the autocorrelation function is at the peak value; and setting a finger weight for the rake finger based on the peak value stored in the storage device.
 2. A method of training a rake finger, as recited in claim 1, further comprising saving the current acquisition phase in the storage device when the autocorrelation function is at the peak value.
 3. A method of training a rake finger, as recited in claim 1, wherein the autocorrelation function is computed by varying the current acquisition phase of the locally-generated signal against the data signal, and passing the autocorrelation function through a filter to obtain an estimate of finger weight.
 4. A method of training a rake finger, as recited in claim 3, wherein the filter is one of: matched to the autocorrelation function, and approximately matched to the autocorrelation function.
 5. A method of training a rake finger, as recited in claim 3, wherein the filter is one of: an infinite impulse response filter, and a finite response filter.
 6. A method of training a take finger, as recited in claim 3, wherein the peak value is determined by finding a maximum output of the filter over an interval of phase offsets.
 7. A method of training a rake finger, as recited in claim 1, wherein the peak value is determined by finding phase locations at which a derivative of a filter output changes sign from positive to negative.
 8. A method of training a rake finger, as recited in claim 1, wherein the finger weight is determined by one of: using the stored peak value directly as the finger weight, and multiplying the stored peak value by a scaling factor to generate the finger weight.
 9. A method of training a rake finger, as recited in claim 1, wherein the method is implemented in an integrated circuit.
 10. A method of training a rake finger, as recited in claim 1, wherein the method is implemented in an ultra wideband device.
 11. A method of training a rake finger, as recited in claim 1, further comprising: saving the current acquisition phase in the storage device when the autocorrelation function is at the peak value; setting the current acquisition phase to a new acquisition phase; repeating the calculating of the autocorrelation function, the determining when the autocorrelation value is at a peak value, the saving of the peak value, and the saving of the current acquisition phase one or more times, wherein a plurality of pairs of peak value and acquisition phase are stored in the storage device, each acquisition phase corresponding to one of the plurality of signal components, wherein the finger weight for the rake finger is set based on one of the peak values stored in the storage device.
 12. A raking finger, comprising: an analog receiver circuit for receiving a data signal including a plurality of signal components having a plurality of signal phase values, respectively, and performing analog signal processing operations on the data signal to produce a processed analog signal; an analog-to-digital converter for converting the processed analog signal to a digital signal; a code processor for correlating a codeword against on the digital signal to produce a processed digital signal; a matched filter for processing an autocorrelation waveform in the processed digital signal to produce a filtered autocorrelation value; a peak detector for determining when the filtered autocorrelation value has a peak value; a storage element for storing one or more peak values; and a mixer for mixing the processed digital signal with a finger weight value derived from the one or more peak values.
 13. A raking finger, as recited in claim 12, wherein the finger weight value is equal to one of the one or more peak values stored in the storage element.
 14. A raking finger, as recited in claim 12, wherein the storage element also stores one or more phase values associated with the one or more peak values, respectively.
 15. A raking finger, as recited in claim 12, further comprising an alignment circuit for aligning symbols of the processed digital signal with corresponding symbols in other processed digital signals in other raking fingers.
 16. A raking finger, as recited in claim 12, further comprising a scaling circuit for multiplying one of the peak values stored in the storage element by a scaling value to generate the finger weight value.
 17. A raking finger, as recited in claim 12, wherein the analog receiver further comprises a local oscillator mixer for mixing the data signal with a locally-generated signal.
 18. A raking finger, as recited in claim 12, wherein the matched filter is one of: an infinite impulse response filter, and a finite response filter.
 19. A raking finger, as recited in claim 12, further comprising an antenna for receiving a wireless signal and providing the wireless signal to the analog receiver circuit as the data signal.
 20. A raking finger, as recited in claim 12, wherein the rake receiver is implemented in an ultra wideband device.
 21. A raking finger, as recited in claim 12, wherein the rake receiver is implemented in an integrated circuit.
 22. A raking receiver, comprising: first through K^(th) raking fingers, each receiving a data signal including a plurality of signal components having a plurality of signal phase values, respectively, and providing first through K^(th) weighted data signals, respectively; and a rake processor for receiving the first through K^(th) weighted data signals and processing them to generate a signal estimate, wherein each of the first through Kraking fingers further comprises: an analog receiver circuit for receiving the data signal and performing analog signal processing operations on the data signal to produce a processed analog signal; an analog-to-digital converter for converting the processed analog signal to a digital signal; a code processor for correlating a digital codeword against the digital signal to produce a processed signal; a matched filter for processing an autocorrelation waveform in the processed signal to produce a filtered autocorrelation value; a peak detector for determining when the filtered autocorrelation value has a peak value; a storage element for storing one or more peak values; and a mixer for mixing the processed digital signal with a finger weight value, and wherein K is an integer.
 23. A raking receiver, as recited in claim 22, wherein the storage element also stores one or more phase values associated with the one or more peak values, respectively.
 24. A rake receiver, as recited in claim 22, further comprising an antenna for receiving a wireless signal and providing the wireless signal to the first through K^(th) raking fingers as the data signal.
 25. A raking finger, as recited in claim 22, wherein the rake receiver is implemented in an ultra wideband device.
 26. A raking finger, as recited in claim 22, wherein the rake receiver is implemented in an integrated circuit. 